1. Field of the Invention
The present invention relates to a semiconductor package. More specifically, the present invention discloses an image sensor semiconductor package comprising a vision chip and a wire shielding block protecting the semiconductor chip bonding wires.
2. Description of the Prior Art
Numerous electronic devices, such as digital cameras, personal digital assistants, and internet appliances, utilize image sensors. As these electronic devices become smaller and smaller, the associated semiconductors used in the electronic devices are forced to become more compact and more efficient. Also, a highly competitive industry and economy is requiring more reliable components at a lower cost.
Image sensors are basically semiconductor devices that are capable of electronically capturing visual information so that this data can be processed or viewed.
As useful as image sensors are, conventional image sensor devices are prone to failure and are relatively expensive to manufacture.
The conventional device basically consists of multiple layers of ceramic material to form a ceramic housing with electrical leads protruding through the sides of the ceramic housing. This ceramic housing is produced by multiple layers of expensive ceramic material. Once a chip has been attached inside the housing, a glass cover is glued to the top of the housing. The glass cover is essentially the same size as the ceramic housing.
The conventional device as described above, has several disadvantages. For example, the glass cover can easily separate from the ceramic package. This is due to the fact that the bond between the glass and ceramic material is not strong. As a result of this delamination, the chip is exposed to the external environment thereby destroying the device.
Ad Another problem is that moisture can enter the porous ceramic package which causes condensation on the inside of the glass thus degrading the image capturing ability and quality of the chip.
Additionally, the ceramic material used in the conventional device is relatively expensive. Requiring multiple layers of expensive ceramic material makes the production cost of the convention device high as well as requiring extra processing steps.
Furthermore, the construction of the conventional ceramic device does not allow for providing the lowest profile or most compact package as possible.
Therefore, there is need for an improved image sensor semiconductor package with improved moisture resistance, lower cost, higher reliability, and more compact profile.
To achieve these and other advantages and in order to overcome the disadvantages of the conventional device in accordance with the purpose of the invention as embodied and broadly described herein, the present invention provides an image sensor semiconductor package comprising a vision chip and a wire shielding block protecting the semiconductor chip bonding wires with improved moisture resistance higher reliability, lower production cost, and more compact size.
Basically, the image sensor semiconductor device of the present invention comprises a multi-layer resin mask organic substrate, a semiconductor chip, a vision chip active area, conductive wires, a wire shielding block, a transparent window, and encapsulant.
The multi-layer resin mask organic substrate is a substrate comprising a resin mask and an organic substrate of the same material. Utilizing the same materials allows the substrate to be extremely flat. The circuit traces formed by the resin mask that are in the substrate material are even, thus providing a very flat substrate surface. Therefore, there is better placement of the semiconductor chip and greater adhesion between the semiconductor chip and the substrate.
A semiconductor chip is bonded, for example, adhesively bonded, to the multi-layer resin mask organic substrate by means of an adhesive. The semiconductor chip comprises a vision chip active area. The vision chip active area may be comprised as a part of the semiconductor chip or a separate chip. The vision chip may comprise a complementary metal oxide semiconductor (CMOS) or a charge-coupled device (CCD) vision chip.
A plurality of conductive means are bonded or attached between conductive contacts or traces on the active side of the semiconductor chip and the multi-layer resin mask organic substrate. The conductive means comprise, for example, gold bonding wires. The conductive means are utilized to create selective electrical connections between conductive contacts, pads, or traces on the semiconductor chip and traces or contacts of the multi-layer resin mask organic substrate.
A transparent window is placed on top of the semiconductor chip covering the vision chip active area. The transparent window comprises, for example, a boro-silicate glass window, other transparent material, or a lens.
A wire shielding block is formed on the multi-layer resin mask organic substrate around the semiconductor chip. The size of the wire shielding block can be made to a desired height and width so that the bonding wires are covered. The wire shielding block protects the conductive means. While forming the wire shielding block, very low pressure is put on the bonding wires. Therefore, the wires are not distorted. Once formed, the wire shielding block ensures that the wires never touch the chip edge so the semiconductor chip will not be damaged. In addition, the wire shielding block shields the conductive means from the environment or accidental damage before and during encapsulation.
A liquid encapsulant is formed to cover desired areas and portions of the multi-layer resin mask organic substrate, the wire shielding block, and the edges of the transparent window. The encapsulant completely covers the wire shielding block. However, care is taken to ensure that only a portion of the transparent window is covered by the encapsulant. The encapsulant does not cover parts or portions of the transparent window that would cover the vision chip active area thereby interfering with the operation of the vision chip active area. For proper operation, the vision chip active area must be able to have clear vision to the external environment through the transparent window. Therefore, the encapsulant must not block the clear vision of the vision chip active area. The encapsulant adhesively fixes and protectively seals the image sensor semiconductor package thereby shielding the semiconductor chip and vision chip active area from the external environment. Additionally, since the substrate is a resin mask organic substrate and very flat, the adhesion between the substrate and the encapsulant is very strong.
The image sensor semiconductor package can be finished by processing methods to complete the device if needed, prior to or after encapsulation. For example, depending on packaging type, preparing contact areas for inputs and outputs of electrical signals to the semiconductor device. Various package types are provided for in the present invention. For example, the final package type can be a ball grid array (BGA), leadless chip carrier (LCC), quad flat pack (QFP), and quad flat no-lead (QFN) package types, or other package types.
The image sensor semiconductor package of the present invention enjoys numerous advantages and benefits. The flatness of the substrate, the similarity of the materials and properties, and the greater adhesion between materials, provides for a highly reliable and moisture resistant image sensor device. Also, the bonding wires are completely protected by the wire shielding block. The wire shielding block also ensures that the wires never touch the chip edge so the semiconductor chip will not be damaged. In conventional devices, the unprotected wires are often bent or distorted during encapsulation thus increasing the rejection rate. Utilizing the wire shielding block of the present invention allows for an increased yield rate. In addition, the ceramic material of the conventional device is more expensive than the organic material utilized in the image sensor semiconductor device of the present invention. Therefore, an advantage of the present invention is the benefit of reduced production cost. Furthermore, an advantage of the present invention is an extremely low profile. Since no space is required between the semiconductor chip, vision chip active area, and the transparent window, the overall height of the device is reduced. This allows the image sensor semiconductor package of the present invention to be more compact thereby increasing the value of the device.
Therefore, the present invention provides an image sensor semiconductor package comprising a vision chip and wire shielding block with improved moisture resistance, lower cost, higher reliability, and more compact size.
These and other objectives of the present invention will become obvious to those of ordinary skill in the art after reading the following detailed description of preferred embodiments.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.